This section provides background information related to the present disclosure and is not necessarily prior art.
Vehicles that have flip-up style rear doors (i.e. liftgates), such as SUVs, vans, or hatchbacks for example, are typical constructed with an inner panel disposed toward an interior side of the vehicle, an outer panel disposed toward an exterior side of the vehicle, and a window pane disposed in an upper section of the liftgate. The inner panel is typically stamped or pressed from a single sheet of metal, such as steel or aluminum, into a shape that generally contours to an opening to the rear of the passenger compartment or trunk area of the vehicle. The shape of conventional inner panels includes a large, generally rectangular opening for the rear window in the upper section of the inner panel. The liftgate is typically hinged to the vehicle structure, such as at a header of a vehicle body, to allow pivotal movement of the liftgate to open the liftgate. The liftgate and vehicle body typically include a latching mechanism to secure the liftgate to the vehicle body when closed. Conventionally constructed liftgates pose a number of issues that are improved upon by the present teachings.
Conventional liftgates contribute significantly to the overall weight of the vehicle. With increasing demand for greater fuel economy, reducing the weight of the liftgate is one target for increasing fuel economy. One method of reducing the weight of the liftgate is to cast the inner panel from a lighter material, such as magnesium for example, instead of press molding or stamping it from steel or aluminum. Magnesium casting is a relatively new method in the art of vehicle liftgates, and due to the size and complexity of liftgates relative to conventionally die cast parts, it raises many new challenges. The size of the rear window pane is also a significant target for reducing the weight of the liftgate. However, the sprue and gates of the casting die and platen are typically located within the envelope of the rear window opening. Decreasing the size of the inner panel's rear window opening reduces the area available for introducing the molten magnesium into the mold through the sprue and gates. Decreasing the size of the rear window opening also increases the size of the liftgate's lower section (i.e. the area below the rear window opening). The larger the lower section of the inner panel, the further that the molten magnesium must travel through the casting mold to reach the outer periphery of the inner panel. Long travel distances can cause the molten metal to cool and begin to solidify before reaching all portions of the mold. This cooling can prevent adequate flow through narrower areas of the mold, thus effectively limiting the minimum nominal thickness of the inner panel, and thus the minimum weight achievable.
Conventionally constructed liftgates can vibrate and move relative to the vehicle's body or can have internal vibrations relative to different parts of the liftgate. Stabilization of the liftgate is important to reduce undesirable noise of the vehicle and wear on the liftgate and vehicle body. To stabilize the liftgate, the liftgate should be prevented from traveling cross-vehicle, fore/aft, and vertically during movement and vibration of the vehicle body and liftgate. Various components of the liftgate (e.g. speakers, inner or outer panels) should be prevented from moving relative to other proximate components (e.g. inner or outer panel). Prior attempts at stabilizing the liftgate involved draft angles and geometry that required separate parts to be mounted to the liftgate. These additional parts increase the time and cost of assembling the liftgate.
Conventionally constructed liftgates that include taillights typically have a set of taillight cans into which the taillights are mounted. Conventional taillights require a taillight can of a significant depth. To achieve such a depth, conventionally constructed liftgates require taillight cans that are separately stamped parts, as the depth and draft angles are too severe for stamping into the inner panel. These separate taillight cans are subsequently mounted to the liftgate and seal with the outer panel of the liftgate to prevent liquid from getting between the inner and outer panels. These separate taillight cans add cost and time to the manufacturing process.